Search results for "Exchange"
showing 10 items of 2035 documents
Kinetic and equilibrium study for cadmium and copper removal from aqueous solutions by sorption onto mixed alginate/pectin gel beads
2013
Abstract Kinetic and equilibrium studies have been carried out to evaluate Cd(II) and Cu(II) sorption from aqueous solution by calcium alginate and new synthesized hybrid calcium alginate/pectate gel beads with different alginate/pectate concentration ratios. Physical and chemical properties of the beads were characterized by different techniques (SEM, EDX, TGA). The best experimental pH conditions were selected on the basis of a study on the acid–base properties of pectin and alginate in aqueous solution and their ability to act as sequestering agents for copper(II) and cadmium(II) ions. Calcium released during the sorption process was determined in order to elucidate a possible ion exchan…
Sorption of Pd(II) ion by calcium alginate gel beads at different chloride concentrations and pH. A kinetic and equilibrium study
2016
Abstract A kinetic and thermodynamic study on the sorption ability of calcium alginate gel beads towards Pd(II) ion was made in aqueous solution at different pH and chloride concentrations. The experimental conditions adopted in the sorption experiments were established on the basis of a speciation study on the Pd 2+ -AA system in which all the side reactions, such as the hydrolysis of Pd(II), the protonation of alginate and the interactions of the ligand and the metal ion with ions of ionic medium were taken into account. In the pH range 2–5 and at chloride concentration in the range 0 ⩽ C Cl - /mmol L −1 ⩽ 10 the gel beads showed good sorption ability towards Pd(II) ion as confirmed by k…
Sorption and mechanism studies of Cu2+, Sr2+ and Pb2+ ions on mesoporous aluminosilicates/zeolite composite sorbents
2020
Abstract The research aimed to develop a novel mesoporous aluminosilicate/zeolite composite by the template co-precipitation method. The effect of aluminosilicate (AlSi) and zeolite (NaY) on the basic properties and adsorption capacity of the resultant composite was conducted at different mass ratios of AlSi/NaY (i.e., 5/90, 10/80, 15/85, 20/80, and 50/50). The adsorption characteristics of such composite and its feedstock materials (i.e., aluminosilicates and zeolite) towards radioactive Sr2+ ions and toxic metals (Cu2+ and Pb2+ ions) in aqueous solutions were investigated. Results indicated that BET surface area (SBET), total pore volume (VTotal), and mesopore volume (VMeso) of prepared m…
Synthesis of zeolite/geopolymer composite for enhanced sequestration of phosphate (PO43−) and ammonium (NH4+) ions; equilibrium properties and realis…
2021
Abstract Zeolite impeded geopolymer (Z/G) was synthesized from natural kaolinite and diatomite. The structure (Z/G) was characterized as an enhanced adsorbent for PO43− and NH4+ ions from aqueous solutions, groundwater, and sewage water. The synthetic Z/G structure exhibits sequestration capacities of 206 mg/g and 140 mg/g for PO43− and NH4+, respectively which are higher values than the recognized results for the geopolymer and other adsorbents in literature. The sequestration reactions of PO43− and NH4+ by Z/G are of Pseudo-Second order kinetic behavior considering both the Chi-squared (χ2) and correlation coefficient (R2) values. The sequestration reactions occur in homogenous and monola…
Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater.
2015
Abstract Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium (Cd) from spiked high-hardness groundwater (GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by 1 H NMR spectroscopy. Pullulan succinate (Pull-Suc) was converted into the sodium salt (Pull-Suc-Na). The effect of contact time (5–200 min) and pH (2–8) on Cd-uptake by the sorbent (Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water (DW) and GW solution, respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents sugge…
Lanthanide complexes as imaging agents anchored on nano-sized particles of boehmite
2011
International audience; The synthesis of boehmite nanoparticles modified with lanthanides (Eu, Tb and Gd) is described. Their synthesis, characterization and in vitro assays with HeLa cells were performed. The nuclear magnetic relaxation dispersion (NMRD) profiles of the two chelating moieties were studied. Imaging data from laser scanning confocal fluorescence microscopy and flow cytometry revealed that the nanoscaffolds were taken up by the cells, distributed throughout the cytoplasm and showed no toxicity. This platform could represent an alternative to silica-based inert matrices as imaging vehicles.
Production and Radiochemical Separation of the Auger Electron Emitter140Nd
2000
Among the Auger electron emitters, the radiolanthanide 140Nd has some unique nuclear properties with potential for endoradiotherapeutic applications. In the present study, 140Nd was produced via the 140Ce(3He,3n) nuclear process at the FZ Julich CV28 cyclotron, irradiating CeO2 with 3He particles of 36 MeV primary energy. Yields of about 5 MBq 140Nd per microAh were experimentally obtained. Batch yields of > 100 MBq 140Nd were reached. 140Nd was separated in 75 +/- 5% radiochemical yield using a two-step process, first by extracting the bulk of the target material according to a Ce(IV)/Nd(III) separation, then by final ion exchange purification.
Core–Shell Engineering to Enhance the Spectral Stability of Heterogeneous Luminescent Nanofluids
2017
This work was supported by the Spanish Ministerio de Educación y Ciencia (MAT2016-75362-C3-1-R) and by COST Action CM1403. L.L.-P. thanks the Universidad Autónoma de Madrid for the ‘‘Formación de Personal Investigador (FPI-UAM)’’program. P.H.-G. thanks the Spanish Ministerio de Economia y Competitividad for the Juan de la Cierva program (IJCI-2015-24551). M.P. and A.S. thank University of Verona (Italy) for financial support in the framework of the ‘‘Cooperint 2016’’ and “Ricerca di Base 2015” projects. The work of K.S. was supported by Latvian National Research Program IMIS2 (Grant No. 302/2012).
A SIM-MOF: Three-Dimensional Organisation of Single-Ion Magnets with Anion-Exchange Capabilities
2014
The formation of a metal-organic framework (MOF) with nodes that have single-molecule magnet (SMM) behaviour has been achieved by using mononuclear lanthanoid analogues, also known as single-ion magnets (SIMs), which enormously simplifies the challenging issue of making SMM-MOFs. Here we present a rational design of a family of MOFs, [Ln(bipyNO)4](TfO)3⋅x solvent (Ln=Tb (1); Dy (2); Ho (3); Er (4); TfO=triflate), in which the lanthanoid centres have an square-antiprismatic coordination environment suitable for SIM behaviour. Magnetic measurements confirm the existence of slow magnetic relaxation typical of SMMs, which has been rationalised by means of a radial effective charge model. In add…
Synthesis and cation-exchange properties of a bis-zwitterionic lamellar hybrid material
2008
The synthesis of a bis-zwitterionic lamellar hybrid material containing ammonium carboxylate groups is described. Cation-exchange properties of this material towards transition metal and lanthanide ions were studied as well as the regeneration and reuse of the material.